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ZUKIWORLD Discussion Forum => Suzuki 4x4 Forum => Topic started by: windahdah on July 09, 2009, 11:59:04 AM
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OK guys I'm going to spring something on all of you that has not been seen nor heard of yet in the world of suspensions.
Back in February I was granted a "provisional patent" for a totally new type of vehicle suspension. Termed the "VX" suspension it offers numerous advantages over any other type of suspension, and my Sidekick was the inspiration for inventing it.
Basically I wrestled in my mind for several years going "why CAN'T an independent suspension have as much or more travel than a solid axle?". This led me through several iterations of my concept until I arrived at the last one, for which I've applied for the patent. I'm attaching the patent application which has a bunch of legalese but just FFWD through that and get to the admittedly lame drawings I've done. I think you'll get the idea.
I believe that with enough careful packaging my design could approach 30" of travel in a Sidekick, the room in the chassis the only limiting factor. This is with a fully independent design mind you!
Now the BIG news? In "stumbling" upon this design I realized that, happily, I had just invented a suspension that has NO camber change and NO wheel scrub throughout the wheel's travel! Eliminating those two bugaboo's has been regarded as the "holy grail" of suspension designs. With further development of the steering system (traditional tie-rods won't work) I also have invented a suspension that has NO bump-steer or deflection steer. The wheels quite simply move up and down in a perfect plane! In essence the VX suspension approaches the theoretical ideal.
In order to make this suspension go I'll need to use "slip-yoke" style telescoping half-shafts on either side of the diffs. Similarly a slip-yoke design would be necessary for the steering to work as well but neither of those things is earth-shattering...Live axles use a slip-yoke driveshaft with regularity, I'm just doing the same thing on the half-shafts.
I'm currently developing the suspension prototype in an RC car format, 2wd only and only the front suspension. Basically I'm doing the minimum to satisfy the requirements of the US patent office.
Any feedback/advice from you guys would be great. If any of you fabricator guys out there have any interest in developing this suspension with me I'm more than willing to grant exclusive rights to the Zuki market for nothing other than your time and effort.
So in a nutshell here's what I believe the VX suspension can achieve:
1) Up to or more than 40" of travel given enough chassis room, 20-30" for most production cars/trucks.
2) Full independence with low un-sprung mass.
3) NO chamber change.
4) NO wheel scrub (the vehicle track width remains static at all times).
5) NO bump steer or deflection steer.
6) The ability to raise the ride height (by using air springs) w/o affecting track width. This would allow the driver to set the ride height depending upon the demands of the trail/road.
Since applying for the patent I have come up with yet another advance that would allow camber change if desired. In essence what I can accomplish with this design is BOTH positive AND negative camber. The wheel would go into positive camber upon compression and negative camber upon decompression. Essentially this would allow the suspension to compensate for body roll, thereby allowing the wheels to remain at 0 degrees camber at ALL times. Furthermore by adjusting the length of the links the rate of camber change could be raised from none to a lot if desired. If you want to get really crazy the system could be made "active" and adjust the length of said links on the fly....meaning the wheels would NEVER go out of camber even when there is no body roll.
I realize that this sounds like Pie-in-the-sky but I promise you it's for real. I would love nothing more than to see the Sidekick be the first vehicle to get what I consider to be the worlds most advanced suspension.
Please view the attachments if you'd like to. The steering system is drawn up for an RC car servo steering but could easily be modified to a rack and pinion type input instead.
I look forward to your feedback.
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Looks nice on the first glance ;) Gotta dive in it further to see how it works.
The limiting factor for kicks however are the cv's and this doesn't help them right?
I'll dive in a bit more and will try to get some more positive critism your way ;D
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Yes, no doubt the CV's are the weak point and the suspension doesn't help 'em out by offering so much travel. To be sure some really burly and high-angle CV's will need to be used. I never said this suspension was the cheapest but I will say that it's the best.
Please do think it over and let me know what you come up with. Be ware though...this gets into your brain and you can't get it out. If you're like me you'll find yourself thinking about the design at all hours of the day/night ;-). And I hope you and many others are like me in that regard....the more the better.
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With a brief look I think the biggest problem is all the moving parts. There are a lot of things to break.
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If you trully care for our input, a clear draft of the suspension would help. Able to down load a steering (rough) draft but nothing on the suspension. Most of us know "less is more" when it comes to off road. Still mother nature may be your best judge. ;)
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thinking about it for like half an hour now and I think I get it now >:D.
Problem indeed would be a lot of moving parts per wheel, with at least 10 individually pivoting parts the tolerances involved in keeping it tight would be quite hard to fab for a do it yourself guy (like all of us)
the geared version would prolly make it better though.
In theory it looks awesome indeed, but I think having only 1 degree of freedom without having any play in any way (wich is basically the strenght of the design) is also the weekness, cos it's kinda over-constrained.
once I get my 3d drawing program working again I'll draw it up and look at the effects the longer/shorter links and different pivot points have on the position and camber and stuff.
For now I'd say good thinking but a pretty complicated design with kinda collides with the kiss (keep it stupid simple) way of thinking I tend to apply ;)
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Agree with many of the above comments - took me a while reading through and flipping back and forth from text to diagrams - but I eventually got the gist of it - showing a wheel attached to the carrier in the diagrams would have made it so much easier.
Now - the no scrub "thing" - this is dependent on the upper half and the lower half moving the exact same amount vertically, but, as far as I can tell, with the current design, there is nothing guaranteeing this. Theoretically it will happen, but the reality may well be different.
Next - camber - this design is dependent on the vehicle chassis remaing level (horizontal) and the suspension moving in a perpendicular plane, relative to the chassis, in which case the wheel will remain at the desired camber (which is not always zero). Consideration needs to be given to the occasions when the vehicle chassis is not horizontal, such as in a turn, when body roll may occur, especially if the vehicle is raised.
My suspicion is that this design may allow roll to tilt the chassis to the point where the negative camber on the outer wheels becomes zero and heaven forbid, even positive - by comparison - a mcpherson strut, as the chassis rolls onto the strut, and the lower arm moves upward (relative to the chassis), the negative camber increases, helping to keep the outer tire squarely planted on the road surface.
Conceivably - this could end up being a "low speed, long travel" suspension design, better suited to off road activities, rather than on road.
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Conceivably - this could end up being a "low speed, long travel" suspension design, better suited to off road activities, rather than on road.
Wouldn't this need some sort of certification from an engineer to be used & marketed for on road use?
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How do you plan to keep the toe angle correct with this design?
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How do you plan to keep the toe angle correct with this design?
I think the only realistic way would be to use twin hydraulic cylinders one controlling each side. or use a modified rack and pinion setup on each side connected by a splined slip shaft to a frame mounted rack and pinion.
The big question for me is, if I am looking at the drawings correctly. The design would require a big honkin horizontal lower control arm which would move up and down with the tire. It looks to me like they would allmost meet in the middle of a vehicle the size of a kick. The system would also have to be way overbuilt to withstand the beating it would take being that low and exposed. What advantage would there be to a system which would have less under body clearance than both independent and solid axle suspensions the lack of camber change not withstanding.
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I really feel your concerns vis ground clearance are unfounded.
I recon the "wheel carriage" would need need to provide about a foot difference between the inner pivot points and the outer pivot points. Basically a wider space between them provides better leverage and a shorter one less leverage, meaning if you shortened the distance between the wheel carriage pivots then you'd need stronger arms to deal w/ the added stress on the arms.
Independent designs provide better ground clearance than live axles. They don't articulate as well, that's the rub. My design might be slightly more vulnerable to a rock right next to the wheel knocking the wheel carraige but not much more so than any A-arm design.
In other words the "wheel carraige" doesn't need to be that long/wide at all like you describe. Furthermore the wheel carrier could be made to be ABOVE the spindle/hub whereas most current IFS' mount em below, that could allow more "clearance".
Toe angle should be solved by the steering system that doesn't use traditional tie-rods. Believe me, this suspension will track truer than any other design. There will be absolutely NO bump steer. The toe angle can be set to whatever you want and it will remain static at all times.
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Hey all--
Prototype #1 of the VXI suspension is now done. I'm working on prototype #2 currently and it'll be a major advance over #1 but still, the idea is the same.
In other GREAT news Racecar Engineering Magazine has agreed to write an article on my suspension!
Here are some pix of the Prototype #1, please feel free to give me your feedback. Thanks...
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More pix....
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One more....
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The steering is interesting, I wonder how well it will scale up to larger vehicles.
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great thinking. read books by carol smith. there are so many variables in suspension. scrub, bump steer camber change all have their places.
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Lot of articulating joints to maintain.
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From the looks of it - that would not be feasible on production vehicle. The inward movement would not allow much space for an engine, assuming a traditional front engine, rear wheel drive - or luggage space, assuming rear engine, rear wheel drive.
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Thanks for the input guys, but please bear in mind that this is the 1st prototype of many. I hear your collective concerns regarding weight, complexity and intrusion into the chassis. I assure you all that these concerns will be addressed in forthcoming prototypes. I have a plan to address every one of these issues.
I promise you that the VXI will be the most compact independent suspension there is for any given amount of travel. For instance prototype #2 will have "nested" legs that will make it far more compact than version #1 is by allowing one set of legs to eat into the space taken up by the other legs. Prototype #1 is as basic as can be since I was just making it up mostly on the fly, now that I've built the first one I've learned a lot and will use that knowledge to improve things in prototype #2 by vast margins.
Rigidity will be addressed by moving to a "T" configuration on the legs where one set of legs is oriented "east-west" an the other set of legs "north-south". This will also help packaging in real cars. Also bear in mind that prototype #1 has 3.5" of travel potential whereas the stock SLA setup on that chassis had but 1.5" of travel. Believe me when I say that if I only had designed it to match the 1.5" of travel it would be far more compact than depicted.
Weight will be addressed by reducing the amount of metal used in the "wheel carraige" and other components. Obviously this was built in my garage, not by a CNC machine so there's a LOT of refinement left to be done. Prototype #1 is just a proof of concept, prototypes #2 and more will advance the design significantly so stay tuned.
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looks like it would work but how much abuse can this take once made full scale? looks unique and wish you the best in your developpement. progress is always a journee and stay positive.
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The picture of the steering bottom looks like the week spot if used in a real car or buggy.
From rocks ect....
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That is the spirit that made this such a great country. Best wishes to you on your quest!
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Hello All Zuki fans. At long last as requested I've recorded a video and posted it on YouTube....
VXI V2Prototype (http://www.youtube.com/watch?v=-Mq3gpBWU1E#)
Enjoy!
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Lets say everything works great. How would you be able to produce this in a cost effective manner that averge 4wd enthusiasts can afford?
Due to the seemingly complex design I would think that folks will look for the most affordable item that would give them the hight, flexibility, quality, strength, and performance for the least amount of $$$$.
I like the concept but I have a feeling that the final cost may limit those who would be willing to purchase.
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Well parts count is certainly higher and therefore cost will be too, there is no doubt. I would like to think that the combination of markedly improved tire-wear, somewhat better fuel-efficiency and of course all the potential performance gains will be enough to off-set the additional expense.
The VXI does lots of things never before possible in a suspension. I guess I'd say if you want the best you'll have to pay for it, simple as that. The VXI should radically outperform any prior design by a fair margin and you'll definitely get longer tire-wear (much longer) along with better gas mileage (5%ish) as well as a rig that is safer, rides smoother, handles better, stops better, goes better, is far more stable....All of that comes at a price, what can I tell ya.
That said I'm really not looking to put this in rigs on a retrofit fashion, it's just way too different for that to be an easy thing to engineer. I do think it can be build on race rigs and then hopefully put into some production vehicles. As for kits to retrofit an old Sidekick or something, that's something I'd love to see but I'm not sure it's worth it from a development cost perspective.
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That makes sense to me and I believe you will find there is a market availble for your product.... Good Luck and thanks for sharing with us for a 1st class 1st hand look!
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As far as steering way to many parts to bind and such. I work in the marine industry and you should look at a twin outdrive system on a volvo DPH drive. They have several styles available but the one for a twin hulled boat without the tie bar would work best. I'll try and bring a picture back from work today. Heck then no steering shaft to get in the way and yes it's still power assist. Then we can add an auto pilot. Sky is the limit.
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i just see way too many parts to fail. engineering is great, and the design is interesting, but for production, simplicity and reduction of parts to fail under warranty will always be favored above performance/tire wear. it's all about economics with the auto makers, and this design is far to un-economic to see on new cars.
as for racing, i could see some advantages with the design, unfortunatly the steering looks like a BIG weakness to me. the need for the shaft to slip up and down in the vertical rotary shaft would be very hard to eliminate all the "slop" involved with it's need to move, thus making the steering sloppy and unresponsive.
dont give up though, this kinda shit is what still makes it worth living in this country!
my $.02
locjaw
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That video seems to show massive camber changes as the suspension cycles - wasn't one of the design goals to have no camber change?
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That video seems to show massive camber changes as the suspension cycles - wasn't one of the design goals to have no camber change?
Yes initially that was the case, zero camber change. Then of course I learned that camber change is desirable but only when cornering. On the V1 prototype camber is fixed and never changes. On the V2 prototype the camber change can be set to be either a lot or zero depending on the placement of the camber-link on the longitudinal arm. On the V3 which I'm working on now the camber-link will be made active so that it combines the performance of V1 and V2.
Essentially when traveling in a straight line camber-change is not desirable yet when cornering it is desirable. The V3 prototype will do exactly that, offer zero camber change under braking dive or acceleration squat and in bump/jounce like when your tire hits a bump while traveling straight ahead. Yet when cornering the camber-link will be made to move up the longitudinal arm such that as much or as little camber-change as you'd like can be designed into the system. In this fashion the VXI can optimize camber at all times and therefore also maximize tire grip while also minimizing tire wear and improving fuel economy too.
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I would have though that you'd also want to minimize both brake dive & acceleration squat, rather than minimize the castor change when they occur.
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I would have though that you'd also want to minimize both brake dive & acceleration squat, rather than minimize the castor change when they occur.
Well actually the high roll-center of the VXI ought to minimize dive and squat in the first place, you're right. Even beyond that grip while braking/accelerating should be improved because the tires remain a optimal camber (not castor, that's totally different and is no different on the VXI than really any other suspension) and the lack of scrub ought to factor in as well.
When a normal independent suspension gets dive/squat the camber changes to something less than optimal (really it's less than optimal to begin with and then gets worse) as well as scrubbing out/in which increases tire wear, builds excess tire heat and ultimately decreases grip.
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Whoops - that castor is a typo - it should have said camber, I do know the difference.
With regard to camber change in a " normal independent suspension" under dive/squat - that would depend on your definition of normal - I believe the most common independent suspension would probably be McPherson strut and yes camber change occurs there, however vehicles do exist (and I have owned one such vehicle) with independent suspension on which the camber does not change with the vertical movement of the suspension, provided that both left & right sides rise & fall to the same extent, as would occur with dive & squat.
As far as scrub goes - on that particular vehicle - there was some scrub on the front tires with vertical motion, but none on the rear.
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A double-wishbone is about the best there is for eliminating camber-change during suspension deflection, followed by a multi-link and then a strut. All of them do have some amount of camber change however and the amount varies depending on the geometry of the suspension.
Traditionally there's always been a trade-off with independent designs between high wheel-travel, good roll center and good instant center. A high-travel double-wishbone typically has a very poor instant-center and roll-center. With that design if you try to get a better roll center you generally have to give up travel and probably the instant-center optimization as well. The VXI simultaneously optimizes all these aspects without any compromises.
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This would be good with in hub electric motors
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There is a new article out in Machine Design Magazine that can be found here:
http://machinedesign.com/article/inventors-corner-a-new-twist-on-a-fully-independent-vehicle-suspension-0504 (http://machinedesign.com/article/inventors-corner-a-new-twist-on-a-fully-independent-vehicle-suspension-0504)
Enjoy!
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This would be good with in hub electric motors
I like the sound a that!